Visual sensor

摘要

A visual sensor capable of expanding a dynamic range with a little load of processing for arithmetic operations and performing a stable detection not affected by change of conditions such as ON/OFF state of projection of reference light. A multiplying parameter A (A>1) and the number N of times of image capturing are set in accordance with ON/OFF state of the reference light projection. N images are captured with a shutter speed varying by successively multiplying an initial value by (I/A). Values of density of each pixel in the captured images are summed. Values of constants B and C in equations: 1 = B.Zmax + C; 0 = B.Zmin + C are obtained based on the maximum value Zmax and the minimum value Zmin of the summed values of densities of all the pixels. An output value Z' of each pixel is obtained according to an equation: Z' = B.Z + C, using the determined values of B and C. <IMAGE>